At what point is it safe to say that no such linkages are likely to be found for schizophrenia or other mental disorders? The authors’ suggestion that the genetic contribution of schizophrenia may be "epigenetic, i.e., related to gene expression rather than sequence variation" (p. 803) is intriguing, but I think it also opens the door for another possibility. Perhaps schizophrenia and other mental disorders, even though shown to be heritable in twin studies, are not actually genetic. This, of course, is paradoxical and would require a paradigm shift in our understanding of mental illness and genetics. But the fact of the matter is that the evidence is pointing in that direction, despite what our current scientific bias leads us to believe. The mind is a complex thing, and our attempts to reduce it to genetic loci or epigenetic expression is surely an oversimplification, if not a complete misrepresentation.